Smartphones, tablets, and other wireless devices have become the individual's permanent link to the Internet, which is for most, the central hub for daily business, communication, and entertainment, Most electronic devices have migrated toward a wireless model, incorporating cellular, RadioFrequency (RF), BlueTooth™, and wireless fidelity (WiFi) transmissions, to name but a few, into their architecture. This combined with the already ubiquitous radio and microwave towers in our cities and neighborhoods have resulted in a modern world of manmade electromagnetic radiation to which we are all constantly exposed. Every time a person makes a call, downloads an email, or sends a text message with a portable device, that person experiences a burst of low-level electromagnetic radiation often immediately adjacent to the body. This periodic irradiation persists as long as one carries a wireless device in a pocket, or holds it in their lap or to his or her ear.
While the term radiation is often associated with “nuclear radiation” or “radioactivity,” the word “radiation” particularly in this sense, refers to energy radiating from a source; not necessarily to radioactivity.
Each of the aforementioned transmission protocols operate in an RF band and fall somewhere in the electromagnetic spectrum. Such an RF transmission, or radiation, is the subject of ongoing debate regarding the harmful effects that electromagnetic radiation has on the human body. While the majority of major RF hazards surround occupational hazards such as RF shocks and burns from high-powered antennae, many experts believe that exposure to low-level electromagnetic radiation for long periods of time can result in other harmful effects such as cancer.
Electromagnetic (“EM”) radiation consists of electric and magnetic energy moving together, or radiating, at the speed of light. Radio waves, microwaves, two-way radios, or any signal or energy emitted via an antenna, falls somewhere on the EM spectrum. Ordinarily, EM field, or RF field are terms used to express the presence of some level of EM energy.
On the lower frequency, yet longer wavelength end of the EM spectrum, past visible light, are infrared, RF, and microwave radiation. The latter two, RF and microwave, are the backbone of the vast majority of wireless communications and will be referred to collectively as “RF.”
The RF part of the electromagnetic spectrum is generally defined as that part of the spectrum where electromagnetic waves have frequencies in the range of about 3 kilohertz (3 kHz) to 300 gigahertz (300 GHz). This includes the microwave subcategory, usually regarded as electromagnetic radiation in the 1-170 GHz range.
Electromagnetic radiation results in a physical field produced by moving electrically charged particles, known as an electromagnetic field (“EMF”). The EMF that surrounds electronic devices is produced by electrical conductors and alternating currents. EMF, or at least its RE component, is usually measured in terms of frequency, or Hertz (Hz).
Most high-powered radars and large commercial RF antennae are capable of producing a large EMF with enough energy to change substances on a molecular level by way of ionization. Damage caused by this level of electromagnetic radiation is most often characterized by heating of the human body to the point of “electrostimulation,” or shocks and burns, In extreme cases, ionizing radiation interrupts regular human cellular operation, and often causes the destruction of molecular compositions within cells, possibly resulting in cellular mutations and some forms of cancer.
However, the various portable electronic devices ordinarily employed for personal use do not contain sufficient energy to chemically change substances by ionization, and so is an example of “nonionizing” radiation. However, there have been several studies that suggest long-term exposure to nonionizing electromagnetic radiation, including RF and microwaves, have significant adverse biological effects at low levels. Such energy may have a carcinogenic effect. This is separate from the risks associated with very high intensity exposure, which can cause burns, and not a unique property of the microwave or RF radiation coming from a portable electronic device.
The radiation to which we are exposed—and the associated affects—depends heavily on the frequency, power, and direction of the emitted energy. Antenna transmission paths are described as either directional or omnidirectional. Omnidirectional antennae receive or radiate more or less in all directions. Most mobile systems, such as personal electronics, employ omnidirectional antennae because the relative position of a cellular station or transmission antenna is unknown or arbitrary. They are also used at lower frequencies where a directional antenna would be too large, or to simply cut costs in applications where a directional antenna is not required. Directional or beam antennae are intended to preferentially radiate or receive in a particular direction or directional pattern. Most cellular towers employ this kind of antenna so as to concentrate the energy in specific areas, or lobes, in order to maximize output in specific areas. For instance, most cellular users are on the ground or at least a lower elevation than the towers, thus such transmission paths are directed predominantly down, instead of up into the atmosphere where the energy goes unused.
Similarly, portable wireless devices, such as tablet personal computers (tablet PCs) or smartphones like the Apple™ iPad™ or iPhone™ or countless others operate on multiple frequencies enabling the systems to connect multiple networks via cellular signals, WiFi, or RE, among others. These transmissions are often omnidirectional, transmitted from the antennae in all directions, as the location of a cellular tower is often unknown to the user. This leaves little protection for the user from the EM and RF radiation. Moreover, generally the closer the user is the device's antenna, the more radiated energy that person absorbs.
Power radiated from an antenna decreases logarithmically with distance (d) and wavelength (λ). This phenomenon is known as path loss. Path loss takes into consideration propagation losses caused by the natural expansion of the radio wave front in free space, absorption losses to media not transparent to EM waves, and diffraction losses when part of the radio wave front is obstructed. Path loss is ordinarily used to describe the losses over large distances but it is also useful to describe the loss over short distances such as the approximately 20 cm between the typical user and his or her wireless electronic device versus the person sifting with an iPad in his or her lap. Because the power of radiated EM energy decreases exponentially with the distance (d2) between the antenna and the user, the closer one is to the radiated energy, the more affect the energy will have.
For instance, a user with a tablet PC in his or her lap or a smartphone to the ear is bombarded with the full power of the antenna's signal directed at the body, as the system communicates with a network or networks. Similarly, a user sitting with a tablet PC, such as an iPad™, while watching a movie or checking email is receiving the full power of the radiated signal to his or her legs, only a fraction of the radiated power reaches the user's face, due to the distance and propagation loss.
While research and debate continue over low-level effects, efforts are continually made to shield ourselves and our electronic systems from EMI, though few of those efforts have been made to shield ourselves from the radiation we experience from our own personal wireless electronic devices.
Shielding can be a double-edged sword however. On one hand, shielding offers the desired protection from unwanted EM or RF radiation, but at the same time the phone must still transmit a signal in order to provide the desired connection to the particular network. Too much shielding negatively affects the phone's ability to provide functionality due to the limited ability to transmit and receive signals. Too little, and the user does not receive the desired shielding.
In light of the above, it would be advantageous to develop a lightweight, low cost, customizable, and convenient material that shields the individual from the harmful effects of the electromagnetic radiation from their our own electronic devices while simultaneously maximizing required transmissions to and from the device. It would be further advantageous to provide a device which collects specific radiation from an electronic device, and redirects that radiation away from the user thereby decreasing the exposure to the user.